The character Vengeance is the personification of the retribution that the peasant revolutionaries exact from the French aristocracy under whose yoke they have suffered and starved. In Chapter XXII of Book the Second, Vengeance represents the senseless and savage turn that the revolution has taken, and as the chosen companion and double of Madame Defarge, her entire entity is that of revenge. Thus, she acts as a macabre expression of the theme of the tendency of man towards violence and oppression towards his fellow man. For, while the Marquis and his class have been cruel to the peasants and oppressive, the peasantry, once having acquired power over the aristocrats, are no better. For, by fighting oppression with the murder of the aristocrats, the peasants perpetuate and increase the violence that they themselves have endured. In his depictions of the mobs,a cautionary Dickens points to this evil with the sinister presence of vengeance delighting in the carnage. in fact, in Book the Third, Chapter XV, Dickens writes,
Sow the same seed of rapacious license and oppression over again, and it will surely yield the same fruit according to its kind.
As Madame Defarge has become so irrationally consumed by her desire for vengeance, she leaves her companion Vengeance and becomes its most devoted agent as she seeks Lucie in the single-minded desire to destroy the Darnay/Evremondefamily in its entirety, thus proving the truth of Dickens's cautions to his audience.